Inspiratory Airway Resistance in Respiratory Failure Due to COVID-19

To measure inspiratory airflow resistance in patients with acute respiratory distress syndrome (ARDS) due to COVID-19.

Design: Observational cohort of a convenience sample.

Setting: Three community ICUs.

Subjects: Fifty-five mechanically ventilated patients with COVID-19.

Interventions: Measurements of ventilatory mechanics during volume control ventilation.

Measurements: Flow-time and pressure-time scalars were used to measure inspiratory airways resistance.

Results: The median inspiratory airflow resistance was 12 cm H₂O/L/s (interquartile range, 10-16). Inspiratory resistance was not significantly different among patients with asthma or chronic obstructive pulmonary disease compared with those without a history of obstructive airways disease (median 12.5 vs 12 cm H₂O/L/s, respectively; p = 0.66). Survival to 90 days among patients with inspiratory resistance above 12 cm H₂O/L/s was 68% compared with 60% for patients below 12 cm H₂O/L/s (p = 0.58). Inspiratory resistance did not correlate with C-reactive protein, ferritin, Pao₂/Fio₂ ratio, or static compliance.

Conclusions: Inspiratory airflow resistance was normal to slightly elevated among mechanically ventilated patients with ARDS due to COVID-19. Airways resistance was independent of a history of obstructive airways disease, did not correlate with biomarkers of disease severity, and did not predict mortality.